1. Field of the Invention
The present invention relates to a technique which permits step-wise scrolling, selectively in either of two opposite directions, through a plurality of stored patterns and, particularly, to facilitating the selection of the flash pattern to be produced by an emergency vehicle warning light. More specifically, this invention is directed to a one wire control which enables a flash pattern generator to step, in either of two directions, through a table of instructions commensurate with multiple flash patterns. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
While not limited thereto in its utility, the present invention has been devised for, and is particularly useful in, the selection of a flash pattern to be generated by a high intensity light mounted upon an emergency vehicle. An emergency vehicle warning or signaling light may employ, as the light generator, an incandescent source, a halogen lamp for example, or a gaseous discharge device, i.e., a flash tube or strobe. Such a light generator may also comprise an array of closely spaced light emitting diodes. The control for an emergency vehicle warning light will typically have the capability of causing the generation of a plurality of different flash patterns. These "standard" patterns will be stored in a pattern table as retrievable controller commands.
The operators of emergency vehicles demand the ability to exercise control over the flash pattern produced by their vehicle mounted warning lights. In the prior art the selection of a stored flash pattern often required the vehicle operator to physically access the control for the flash pattern generator and perform some "manipulation", i.e., a circuit modification, and/or required the routing of a multi-conductor cable from the control to a selector module located within the driver's compartment. Manipulative steps such as the setting of multiple dip switches at the typically difficult to reach control, a common prior art method of pattern selection, can not readily be performed in the field. The foregoing problem results from the fact that the flash pattern generator control is typically located remotely from the passenger compartment, in a roof-mounted assembly for example, and hard to access. The use of passenger compartment mounted multi-position selector switches is an equally unsatisfactory manner of addressing the problem of flash pattern variation since the number of available patterns is limited to the relative small number of discrete switch positions and, additionally, the expense and inconvenience of connecting and routing a multi-conductor cable is presented. The use of other more complex means for communicating data between the passenger compartment and pattern generator control, wireless techniques for example, is prohibitively expensive and/or volumetrically inefficient.
It should also be noted that the operating environment of a warning light is relatively harsh. This fact dictates a desire to package flash generator control circuitry in a shock-proof, hermetically sealed manner. Such packaging obviously complicates, and often precludes, access for pattern changing.
To summarize, there has been a long standing desire for an uncomplicated and easily useable method of and apparatus for choosing that one of a plurality of stored command signals which will result in, for example, the production of a desired flashing light pattern.